10
YORK INTERNATIONAL
% CURRENT LIMIT – This key displays the maximum
value of motor current permitted by its programmed
setting. The value is in terms of percent of Full Load
Amps (FLA). If not programmed, the default value is
100%. (See “Programming System Setpoints”, page 14.)
If chiller is equipped with a YORK Solid State Starter,
the system FLA is also displayed. This value is pro-
grammed by the factory and should never be changed.
The Micro Board uses this value to calculate and dis-
play the % motor current parameter that is displayed
when the % MOTOR CURRENT display key is pressed.
Also, proper current limit control depends on the cor-
rectly programmed FLA value. For security reasons, a
special access code is required to program the FLA
value. It should only be changed by a service techni-
cian.
PULL DOWN DEMAND – This function is used to pro-
vide energy savings following the chiller start-up. This
key displays a programmable motor current limit and a
programmable period of time. Operation is as follows:
Whenever the system starts, the Pull Down Demand
Limit is maintained for the programmed time, then the
current limit control returns to % current limit setpoint.
The maximum permitted motor current is in terms of
% FLA. The duration of time that the current is limited
is in terms of minutes (to a maximum of 255). If not
programmed, the default value is 100% FLA for 00 min-
utes. (See “Programming Systems Setpoints”, page 15.)
Thus, no pull down demand limit is imposed following
system start, and the % current limit setpoint is used.
CLOCK – This key displays the day of the week, time
of day and calendar date. If not programmed, the de-
fault value is
SUNDAY 12:00 AM 1/1/92
.
(See “Programming System Setpoints”, page 15.)
DAILY SCHEDULE – This key displays the pro-
grammed daily start and stop times, from Sunday thru
Saturday plus Holiday. If desired, the Control Center
can be programmed to automatically start and stop
the chiller as desired. This schedule will repeat on a 7-
day calendar basis. If the Daily Schedule is not pro-
grammed, the default value is 00:00 AM start and stop
times for all days of the week and the holiday. (Note
that the system will not automatically start and stop on
a daily basis with these default values because 00:00
is an “Impossible” time for the Micro Board. See “Pro-
gramming System Setpoints”, page 16.) Finally, one or
more days in the week can be designated as a holiday
(see description under HOLIDAY setpoint) and the Con-
trol Center can be programmed (usually DAILY SCHED-
ULE setpoint) to automatically start and stop the chiller
on those days so designated. The operator can over-
ride the time clock at any time using the COMPRES-
SOR switch.
Note that if only a start time is entered for a particular
day, the compressor will not automatically stop until a
scheduled stop time is encountered on a subsequent
day.
HOLIDAY – This key indicates which days in the up-
coming week are holidays. On those designated days,
the chiller will automatically start and stop via the holi-
day start and stop times programmed in the DAILY
SCHEDULE setpoint. It will do this one time only and
the following week will revert to the normal daily sched-
ule for that day.
REMOTE / RESET TEMP RANGE – This key displays
the maximum offset of remote LCWT setpoint reset.
This offset is either 10° or 20°F (5.5° to 11.1°C) as
programmed. When in the REMOTE mode, this value
is added to the operator programmed CHILLED LIQ-
UID TEMP setpoint and the sum equals the tempera-
ture range in which the LCWT can be reset. For ex-
ample, if the operator programmed CHILLED LIQUID
TEMP setpoint is programmed with a value of 46°F
(7.8°C) and the remote/reset temperature range is set
at 10°F (5.5°C), then the CHILLED LIQUID TEMP
setpoint can be remotely reset over a range of 46°F
(7.8°C) to 56°F (13.3°C) (46 + 10 = 56) or (7.8 + 5.5 =
13.2). If not programmed, the default value for this pa-
rameter is 20°F (6.7°C).
For additional information on remote LCWT reset, refer
to Form 160.49-PW3.
NOTE: If an Energy Management System is interfaced
to the Control Center for the purpose of re-
mote LCWT setpoint reset, then the operator
programmed REMOTE RESET TEMP RANGE
value determines the maximum value of tem-
perature reset controlled by the Energy Man-
agement System.
DATA LOGGER – This key is used when an optional
printer is connected to the MicroComputer Control Cen-
ter. Refer to Form 160.49-N2 for operation instructions.
SSS MOTOR CURRENT/VOLTS – This key is used on
Solid State Starter applications only. Although this is a
display key, it is used to program the applicable AC
power line voltage range (380VAC, 400VAC, 415VAC,
440-480VAC, 550-600VAC). The MicroComputer Con-
trol Center uses this entry to determine the undervol-
tage and overvoltage shutdown threshold. For each line
voltage category there is an undervoltage and over-
voltage shutdown threshold. If the AC power line volt-
age exceeds these thresholds for 20 continuous sec-
onds, the chiller shuts down and displays
MON 10:00 AM LOW LINE VOLTAGE
